Process for producing nitriles

ABSTRACT

A process for producing a nitrile, which comprises subjecting an alkane and ammonia in the gaseous state to catalytic oxidation in the presence of a catalyst which satisfies the following conditions of (1) and (2): 
     (1) the catalyst is represented by the empirical formula: 
     
         Mo.sub.a V.sub.b Te.sub.c X.sub.x O.sub.n                  (1) 
    
      wherein X is at least one element selected from the group consisting of Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B and Ce, 
     
         ______________________________________                                    
 
    
                 when a = 1,                                                   
            b = 0.01 to 1.0,                                              
            c = 0.01 to 1.0,                                              
            x = 0.01 to 1.0,                                              
______________________________________                                    
 
      and n is a number such that the total valency of the metal elements is satisfied; and 
     (2) the catalyst has X-ray diffraction peaks at the following angles of 2θ in its X-ray diffraction pattern:______________________________________Diffraction angles of 2θ (°)______________________________________             22.1 ± 0.3             28.2 ± 0.3             36.2 ± 0.3             45.2 ± 0.3             50.0 ± 0.3.______________________________________

The present invention relates to a process for producing nitriles. Moreparticularly, it relates to an improved method for producing nitriles byusing alkanes as starting material.

Nitriles such as acrylonitrile and methacrylonitrile have beenindustrially produced as important intermediates for the preparation offibers, synthetic resins, synthetic rubbers and the like. The mostpopular method for producing such nitriles is to subject an olefin suchas propylene or isobutene to a catalytic reaction with ammonia andoxygen in the presence of a catalyst in a gaseous phase at a hightemperature.

For example, there have been reports on a Mo-Bi-P-O catalyst (JapaneseUnexamined Patent Publication No. 16887/1973), a V-Sb-O catalyst(Japanese Unexamined Patent Publication No. 33783/1972, JapaneseExamined Patent Publication No. 23016/1975 and Japanese UnexaminedPatent Publication No. 268668/1989), a Sb-U-V-Ni-O catalyst (JapaneseExamined Patent Publication No. 14371/1972), a Sb-Sn-O catalyst(Japanese Examined Patent Publication No. 28940/1975), a V-Sb-W-P-Ocatalyst (Japanese Unexamined Patent Publication No. 95439/1990), acatalyst obtained by mechanically mixing a V-Sb-W-O oxide and aBi-Ce-Mo-W-O oxide (Japanese Unexamined Patent Publication No.38051/1989). Further, the present inventors have reported on aMo-V-Te-Nb-O catalyst (Japanese Unexamined Patent Publication No.257/1990 and U.S. Pat. No. 5,049,692).

On the other hand, in view of the price difference between propane andpropylene or between isobutane and isobutene, an attention has beendrawn to developing a method for producing acrylonitrile ormethacrylonitrile by a so-called ammooxidation reaction method wherein alower alkane such as propane or isobutane is used as starting material,and it is catalytically reacted with ammonia and oxygen in a gaseousphase in the presence of a catalyst.

However, none of these methods is fully satisfactory in the yield of theintended nitriles. In order to improve the yield of nitriles, it hasbeen proposed to add a small amount of an organic halide, an inorganichalide or a sulfur compound, or to add water to the reaction system.However, the former three methods have a problem of possible corrosionof the reaction apparatus, while the latter water-adding method has aproblem of formation of by-products by side reactions or a problem oftheir treatment. Thus, each method has a practical problem forindustrial application.

Further, methods using the conventional catalysts other than theMo-V-Te-Nb-O catalyst reported by the present inventors, usually requirea very high reaction temperature at a level of 500° C. or higher.Therefore, such methods are disadvantageous in terms of reactormaterial, production cost, etc.

The present inventors have conducted extensive researches on the methodfor producing a nitrile by using an alkane as starting material. As aresult, they have found it possible to produce a desired nitrile inremarkably better yield than conventional methods at a relatively lowtemperature of a level of from 400° to 450° C. without adding a halideor water to the reaction system, by subjecting the alkane and ammonia inthe gaseous state to catalytic oxidation in the presence of a catalystcomprising molybdenum (Mo), vanadium (V), tellurium (Te) and certaintypes of metals and having a certain specific crystal structure. Thepresent invention have been accomplished on the basis of this discovery.

Thus, the present invention provides a process for producing a nitrile,which comprises subjecting an alkane and ammonia in the gaseous state tocatalytic oxidation in the presence of a catalyst which satisfies thefollowing conditions 1 and 2:

(1) the catalyst is represented by the empirical formula:

    Mo.sub.a V.sub.b Te.sub.c X.sub.x O.sub.n                  ( 1)

wherein X is at least one element selected from the group consisting ofNb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B andCe,

    ______________________________________                                                    when a = 1,                                                                   b = 0.01 to 1.0,                                                              c = 0.01 to 1.0,                                                              x = 0.01 to 1.0,                                                  ______________________________________                                    

and n is a number such that the total valency of the metal elements issatisfied; and

(2) the catalyst has X-ray diffraction peaks at the following angles of2θ in its X-ray diffraction pattern:

    ______________________________________                                        Diffraction angles of 2θ (°)                                     ______________________________________                                                     22.1 ± 0.3                                                                 28.2 ± 0.3                                                                 36.2 ± 0.3                                                                 45.2 ± 0.3                                                                 50.0 ± 0.3.                                                   ______________________________________                                    

In the accompanying drawings:

FIG. 1 shows the powder X-ray diffraction pattern of the complex oxideobtained in Example 1.

FIG. 2 shows the powder X-ray diffraction pattern of the complex oxideobtained in Comparative Example 2.

Now, the present invention will be described in detail with reference tothe preferred embodiments.

The catalyst useful for the process of the present invention forproducing a nitrile by reacting an alkane with ammonia by a gas phasecatalytic oxidation reaction, has the above mentioned chracteristics 1and 2.

The complex oxide having such a specific crystal structure can beprepared by the following method.

For example, in the case of Mo_(a) V_(b) Te_(c) Nb_(x) O_(n), addedsequentially to an aqueous solution containing a predetermined amount ofammonium metavanadate, are an aqueous solution of telluric acid, anaqueous solution of ammonium niobium oxalate and an aqueous solution ofammonium paramolybdate in such amounts that the atomic ratios of therespective metal elements would fall in the specified ranges. Then, themixture is dried by evaporation to dryness, a spray drying method or avacuum drying method, and finally, the dried product is calcined toobtain the desired oxide. To efficiently conduct the calcination, theabove dried product may be decomposed under heating at a temperature offrom 150° to 350° C. in air or in an inert gas atmosphere such asnitrogen or argon, prior to the final calcination.

In the process for preparing the specific complex oxide to be used asthe catalyst of the present invention, the calcination conditions areparticularly important. For calcination treatment to prepare anordinally oxide, it is most common to employ a method whereincalcination is conducted in an oxygen atmosphere. However, in thepresent invention, calcination is preferably conducted in an atmospheresubstantially free from oxygen, for example, in an inert gas atmospheresuch as nitrogen, argon or helium. Further, such a gas may contain areducing gas such as hydrogen or a hydrocarbon, or steam. Otherwise, thecaicination may be conducted under vacuum usually at a temperature offrom 350° to 700° C., preferably from 400° to 650° C., usually for from0.5 to 35 hours, preferably from 1 to 10 hours. At a temperature lowerthan this temperature range, formation of the above crystal structurepresenting the high catalytic activities tends to be inadequate. On theother hand, if it exceeds the above temperature range, a part of thecrystal structure is likely to be thermally decomposed, such beingundesirable.

When the content of oxygen in the complex oxide thus obtained, isexamined, for example, in the case of Mo_(a) V_(b) Te_(c) Nb_(x) O_(n),the value of n is smaller than (3a+2.5b+3c+2.5x) which represents thevalue corresponding to the most highly oxidized state of Mo, V, Te andNb, and it is at a level of from 80 to 97% thereof. Namely, the complexoxide having the specific structure to be used as the catalyst of thepresent invention corresponds to a complex oxide obtainable by calcininga dried product of the same starting materials under a usual oxidizingatmosphere except that the oxygen content is slightly smaller.

The catalyst of the present invention is a complex oxide of the aboveformula (1), wherein X is at least one element selected from the groupas defined above. However, X is preferably Nb, Ta, W or Ti, particularlypreferably Nb. Further, with respect to the coefficients in the formula(1), it is particularly preferred that when a=1, b=0.1 to 0.6, c=0.05 to0.4, and x=0.01 to 0.6.

However, the complex oxide is not adequate as a catalyst for thereaction of the present invention if it merely satisfies the compositionrepresented by the formula (1), and it is important that the complexoxide has a certain specific crystal structure.

An index showing that the complex oxide to be used as a catalyst of thepresent invention has the specific crystal structure, is the powderX-ray diffraction pattern. The X-ray diffraction pattern of the complexoxide is characterized in that it shows the following five maindiffraction peaks at the specific diffraction angles of 2θ (as measuredby using Cu-Kα-rays as the X-ray source):

    ______________________________________                                        Diffraction  Center values of X-ray                                                                        Relative                                         angles of 2θ (°)                                                              lattice spacing (Å)                                                                       intensity                                        ______________________________________                                        22.1 ± 0.3                                                                              4.02            100                                              28.2 ± 0.3                                                                              3.16            20 to 150                                        36.2 ± 0.3                                                                              2.48            5 to 60                                          45.2 ± 0.3                                                                              2.00            2 to 40                                          50.0 ± 0.3                                                                              1.82            2 to 40                                          ______________________________________                                    

The intensities of X-ray diffraction peaks may differ depending upon themeasuring conditions for each crystal. However, the relative intensitiesbased on the peak intensity at 2θ=22.1° being 100, are usually withinthe above identified ranges. In general, the peak intensities at2θ=22.1° and 28.2° are higher than others. However, so long as the aboveidentified five diffraction peaks are observed, there will be no changein the basic crystal structure even if there are some peaks observed inaddition to the above five diffraction peaks, and such a complex oxidecan be suitably used for the present invention.

Thus, it is totally unexpected and surprising that the complex oxide notonly has the specific crystal structure but also provides remarkablyhigh catalytic activities as compared with the conventional catalyst inthe reaction to obtain a nitrile from an alkane as starting material.

Further, the materials for the above complex oxide are not limited tothe ones described above. For example, V₂ O₅, V₂ O₃, VOCl₃ or VCl₄ maybe used instead of ammonium metavanadate, and TeO₂ may be used insteadof telluric acid. Likewise, NbCl₅, Nb₂ O₅ or niobic acid may be usedinstead of ammonium niobium oxalate, and MoO₃ or MoCl₅ may be usedinstead of ammonium paramolybdate.

The complex oxide of the formula (1) prepared in the manner as describedabove, has adequate catalytic activities by itself. However, in order tofurther improve the selectivity and yield of the nitrile, it isparticularly preferred to use a catalyst having a certain specific oxidein corporated to the complex oxide. As such a specific oxide, it ispossible to employ an oxide containing at least one member selected fromthe group consisting of antimony, bismuth, cerium and boron. An antimonyoxide is particularly preferred.

The antimony oxide to be incorporated may, for example, be an antimonyoxide such as Sb₂ O₃, Sb₂ O₄ or Sb₂ O₅, and it may otherwise be an oxidehaving a composition of e.g. SbO₂.(Sb₂ O₄). These oxides may be usedalone or in combination as a mixture of a plurality of them. Otherwise,it may be used in the form of a hydrate. Further, in some cases, it ispossible to employ as a solid catalyst a substance prepared byincorporating an organic compound containing antimony, such as ammoniumantimony tartarate or antimony oxalate to the complex oxide of theformula (1), followed by calcination. In this case, the organic compoundcontaining antimony will be converted to antimony oxide by thecalcination.

The bismuth oxide to be incorporated may, for example, be a bismuthoxide such as Bi₂ O₃ or Bi₂ O₄, and it may also be a hydrate such as Bi₂O₄.2H₂ O. These oxides may be used alone or in combination as a mixtureof a plurality of them. In some cases, a salt of an organic or inorganicacid or a hydroxide containing bismuth, such as bismuth hydroxide,bismuth nitrate, bismuth nitrate oxide or bismuth acetate may be addedto the complex oxide of the formula (1), followed by calcination, andthe substance thereby obtained can be used as a solid catalyst. In thiscase, the salt or the hydroxide containing bismuth will be converted tobismuth oxide by the calcination.

The cerium oxide may, for example, be a cerium oxide such as Ce₂ O₃ orCeO₂. These oxides may be used alone or in combination as a mixture of aplurality of them. In some cases, a salt of an organic or inorganicacid, or a hydroxide containing cerium, such as cerium nitrate, ceriumhydroxide, cerium oxalate or cerium acetate, may be added to the complexoxide of the formula (1), followed by calcination, and the product ofthe calcination can be used as a solid catalyst. In this case, the saltor the hydroxide containing cerium will be converted to cerium oxide bythe calcination. The boron oxide is usually B₂ O₃. However, a boric acidor a boric acid ester, such as orthoboric acid, metaboric acid, ethyborate or propyl borate, may be added to the complex oxide of theformula (1), followed by calcination, and the calcined product can beused as a solid catalyst. In such a case, the boric acid or the boricacid ester is believed to be converted to boron oxide by thecalcination.

As a method for incorporating the above mentioned specific oxide to thecomplex oxide, it is advisable to pulverize and mix both materials sothat the contact of the specific oxide with the complex oxide can beeffectively done. The amount of the specific oxide to the complex oxideis usually from 0.0001 to 0.2, preferably from 0.001 to 0.05 by theweight ratio to the complex oxide. After the addition, the mixture maybe used as it is for the reaction to produce a nitrile from an alkane.However, in order to effectively obtain the effects of the addition ofthe specific oxide, it is preferred to calcine the mixture again at atemperature of from 300° to 650° C., preferably from 350° to 600° C.,usually for from 0.5 to 30 hours, preferably from 1 to 10 hours. Theatmosphere for calcination is not particularly limited, but it isusually preferred to employ an inert gas atmosphere such as nitrogen,argon or helium, and the inert gas may further contain a reducing gassuch as hydrogen, ammonia or a hydrocarbon, or steam. Otherwise, thecalcination may be conducted under vacuum.

Even if the specific oxide is added to the complex oxide, followed bymixing and calcination, the X-ray diffraction pattern of the obtainedproduct is substantially the same as that of the complex oxide beforethe addition of the specific oxide, and there is no substantial changeobserved in the crystal structure.

The above catalyst may be used alone. However, it may be used togetherwith a conventional carrier such as silica, alumina, titania,aluminosilicate or diatomaceous earth. Further, depending upon the scaleor system of the reaction, it may be molded into a proper shape andparticle size.

According to the present invention, a nitrile can be producedefficiently by subjecting an alkane to a gas phase catalytic oxidationreaction with ammonia in the presence of the above catalyst.

In the present invention, the alkane as the starting material is notparticularly limited and may, for example, be methane, ethane, propane,butane, isobutane, pentane, hexane, heptane. However, in view of theindustrial application of nitriles to be produced, it is particularlypreferred to employ a lower alkane having from 1 to 4 carbon atoms,particularly propane or isobutane.

The detailed mechanism of the oxidation reaction of the presentinvention is not clearly understood. However, the oxidation reaction isconducted by the oxygen atoms present in the above complex oxide or bythe molecular oxygen present in the feed gas. When molecular oxygen isincorporated in the feed gas, the oxygen may be pure oxygen gas.However, since the purity is not required, it is usually economical touse an oxygen-containing gas such as air.

As the feed gas, it is common to use a gas mixture comprising an alkane,ammonia and an oxygen-containing gas. However, a gas mixture comprisingan alkane and ammonia, and an oxygen-containing gas may be suppliedalternately.

When the gas phase catalytic reaction is conducted using an alkane andammonia substantially free from molecular oxygen, as the feed gas, it isadvisable to employ a method wherein a part of the catalyst is properlywithdrawn and sent to an oxidation regenerator for regeneration, and theregenerated catalyst is returned to the reaction zone. As a method forregenerating the catalyst, a method may be mentioned wherein anoxidizing gas such as oxygen, air or nitrogen monoxide is permitted toflow through the catalyst in the regenerator usually at a temperature offrom 300° to 600° C.

The present invention will be described in further detail with respectto a case where propane is used as the alkane and air is used as theoxygen source. The proportion of air to be supplied for the reaction isimportant with respect to the selectivity for the resultingacrylonitrile. Namely, high selectivity for acrylonitrile is obtainedwhen air is supplied within a range of at most 25 mols, particularlyfrom 1 to 15 mols, per mol of propane. The proportion of ammonia to besupplied for the reaction is preferably within a range of from 0.2 to 5mols, particularly from 0.5 to 3 mols, per mol of propane. This reactionmay usually be conducted under atmospheric pressure, but may beconducted under a slightly increased pressure or a slightly reducedpressure. With respect to other alkanes, the composition of the feed gascan be selected in accordance with the conditions for propane.

The process of the present invention can be conducted at a temperatureof e.g. from 340° to 480° C., which is lower than the temperature forconventional ammooxidation of alkanes. More preferably, the temperatureis from 400° to 450° C. The gas space velocity SV in the gas phasereaction is usually within a range of from 100 to 10,000 hr⁻¹,preferably from 300 to 2,000 hr⁻¹. As a diluent gas for adjusting thespace velocity and the oxygen partial pressure, an inert gas such asnitrogen, argon or helium can be employed. When ammooxidation of propaneis conducted by the method of the present invention, in addition toacrylonitrile, carbon monooxide, carbon dioxide, acetonitrile,hydrocyanic acid, acrolein, etc. will form as by-products, but theiramounts are very small.

Now, the present invention will be described in further detail withreference to Examples and Comparative Examples. However, it should beunderstood that the present invention is by no means restricted to suchspecific Examples.

In the following Examples and Comparative Examples, the conversion (%),the selectivity (%) and the yield (%) are shown by the followingformulas, respectively: ##EQU1##

EXAMPLE 1

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 Nb₀.1 O_(n)was prepared as follows.

In 117 ml of warm water, 4.21 g of ammonium metavanadate was dissolved,and 4.13 g of telluric acid and 15.89 g of ammonium paramolybdate weresequentially added thereto to obtain a uniform aqueous solution.Further, 3.99 g of ammonium niobium oxalate was dissolved in 17.9 ml ofwater and added thereto to obtain a slurry. The obtained slurry wasevaporated to dryness at about 150° C. to obtain a dried product.

This dried product was molded into a tablet of 5 mm in diameter and 3 mmin length by a tabletting machine, followed by pulverization and sievingto obtain a powder of from 16 to 28 mesh. The powder was calcined in anitrogen stream at a temperature of 620° C. for two hours. FIG. 1 showsa chart of the peaks of the powder X-ray diffraction pattern of thecomplex oxide thus obtained, and Table 1 shows the relative intensitiesof the main X-ray diffraction peaks.

Further, the oxygen content in the complex oxide was measured by anoxygen analyzer and was found to be 31.0% by weight. From this measuredvalue, the coefficient n for O (oxygen) was calculated to be 4.25. Thevalue n=4.25 corresponds to 87.6% of n=4.85 which is the most highlyoxidized state of the constituting elements of the complex oxide whereMo is hexavalent, V is pentavalent, Te is hexavalent and Nb ispentavalent.

0.5 ml of the catalyst thus obtained, was charged into a reactor. Then,a gas phase catalytic reaction was conducted at a reaction temperatureof 440° C. and at a space velocity SV of 1,000 hr⁻¹ by supplying a feedgas in a molar ratio of propane:ammonia:air=1:1.2:10. The results areshown in Table 2.

EXAMPLES 2 AND 3

Complex oxides having an empirical formula Mo₁ V₀.4 Te₀.2 Nb₀.1 O_(n)were prepared in the same manner as in Example 1 except that thetemperature for calcination in Example 1 was changed to 500° C. and 600°C.

The results of the powder X-ray diffraction of the complex oxides areshown in Table 1. Further, the results of the gas phase catalyticreactions are shown in Table 2.

COMPARATIVE EXAMPLE 1

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 O_(n) wasprepared in the same manner as in Example 2 except that the niobiumcomponent in Example 2 was not used.

The X-ray diffraction pattern of the complex oxide was totally differentfrom that of Example 1. The results of the gas phase catalytic reactionare shown in Table 2.

COMPARATIVE EXAMPLE 2

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 Nb₀.1 O_(n)was prepared in the same manner as in Example 1 except that calcinationin Example 1 was conducted under an air stream at 350° C. for two hours.The powder X-ray diffraction pattern of the complex oxide thus obtained,is shown in FIG. 2. The pattern is entirely different from the patternin FIG. 1 representing Example 1.

Further, the results of the gas phase catalytic reaction are shown inTable 2.

COMPARATIVE EXAMPLES 3 AND 4

Using the complex oxide of Comparative Example 2, the gas phasecatalytic reaction was conducted under the reaction conditions asidentified in Table 2. The results are shown in Table 2.

EXAMPLE 4

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 Sb₀.1 O_(n)was prepared as follows.

In 117 ml of warm water, 4.21 g of ammonium metavanadate was dissolved,and 4.13 g of telluric acid and 15.9 g of ammonium paramolybdate weresequentially added thereto to obtain a uniform aqueous solution.Further, 1.56 g of antimony chloride oxide was dissolved in 17.9 ml ofwater and mixed thereto. The obtained aqueous solution was evaporated todryness to obtain a dried product.

This dried product was molded into a tablet of 5 mm in diameter and 3 mmin length by a tabletting machine, followed by pulverization and sievingto obtain a powder of from 16 to 28 mesh. The powder was calcined in anitrogen stream at 500° C. for two hours. The results of the powderX-ray diffraction of the complex oxide thus obtained are shown in Table1.

With respect to the complex oxide thus obtained, the gas phase catalyticreaction was conducted, and the results are shown in Table 2.

COMPARATIVE EXAMPLE 4

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 Sb₀.1 O_(n)was prepared in the same manner as in Example 4 except that thecalcination in Example 4 was conducted under an air stream at 350° C.for two hours. The X-ray diffraction pattern of the complex oxide thusobtained, was entirely different from that of Example 4. Further, usingthe complex oxide thus obtained, a gas phase catalytic reaction asconducted, and the results are shown in Table 2.

EXAMPLE 5

A complex oxide was prepared in the same manner as in Example 4 exceptthat 3.38 g of aluminum nitrate nonahydrate was used instead of antimonychloride oxide in Example 4. The empirical formula of the complex oxidethus obtained, was Mo₁ V₀.4 Te₀.2 Al₀.1 O_(n). The results of the powderX-ray diffraction of the complex oxide thus obtained are shown inTable 1. Further, using the oxide thus obtained, a gas phase catalyticreaction was conducted, and the results are shown in Table 2.

COMPARATIVE EXAMPLE 5

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 Al₀.1 O_(n)was prepared in the same manner as in Example 5 except that thecalcination in Example 5 was conducted under an air stream at 350° C.for two hours. The X-ray diffraction pattern of the complex oxide thusobtained, was entirely different from that of Example 5. Further, usingthe complex oxide thus obtained, a gas phase catalytic reaction wasconducted, and the results are shown in Table 2.

EXAMPLE 6

A complex oxide was prepared in the same manner as in Example 4 exceptthat 0.415 g of palladium nitrate was used instead of antimony chlorideoxide in Example 4 and the temperature for calcination was changed to600° C. The empirical formula of the complex oxide thus obtained, wasMo₁ V₀.4 Te₀.2 Nb₀.1 Pd₀.02 O_(n). The results of the powder X-raydiffraction of the complex oxide thus obtained, are shown in Table 1.Further, using the complex oxide thus obtained, a gas phase catalyticreaction was conducted, and the results are shown in Table 2.

EXAMPLES 7 to 23

Complex oxides having the respective empirical formulas as identified inTable 1, were prepared in the same manner as in Example 1 except thatthe proportions of the starting material compounds were changed and thetemperature for calcination was 600° C. in each case. The results of thepowder X-ray diffraction of the respective complex oxides are shown inTable 1. Further, using the respective complex oxides, gas phasecatalytic reactions were conducted, and the results are shown in Table3.

EXAMPLES 24 TO 32

Using the complex oxide prepared in Example 3 (empirical formula Mo₁V₀.4 Te₀.2 Nb₀.1 O_(n)), gas phase catalytic oxidation reactions wereconducted under various conditions, and the results are shown in Table4.

                  TABLE 1                                                         ______________________________________                                        Ex-                   Relative intensities of X-ray                           am-                   diffraction peaks at diffraction                        ple  Complex oxides   angles of 2θ (±0.3°)                    Nos. (atomic ratios)  22.1°                                                                         28.2°                                                                       36.2°                                                                       45.2°                                                                       50.0°                      ______________________________________                                        1    Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                               100    79.5 21.0 10.9 12.3                              2    Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                               100    92.8 18.7 11.5 13.2                              3    Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                               100    93.0 24.9 12.9 14.4                              4    Mo.sub.1 V.sub.0.4 Te.sub.0.2 Sb.sub.0.1 O.sub.n                                               100    122.5                                                                              36.1 12.2 23.0                              5    Mo.sub.1 V.sub.0.4 Te.sub.0.2 Al.sub.0.1 O.sub.n                                               100    97.4 27.6 13.7 20.0                              6    Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 Pd.sub.0.02 O.sub.n                                   100    80.9 21.8 11.1 12.6                              7    Mo.sub.1 V.sub.0.3 Te.sub.0.2 Nb.sub.0.15 O.sub.n                                              100    63.6 17.4 12.4 11.0                              8    Mo.sub.1 V.sub.0.375 Te.sub.0.2 Nb.sub.0.175 O.sub.n                                           100    87.6 25.1 15.6 16.9                              9    Mo.sub.1 V.sub.0.35 Te.sub.0.2 Nb.sub.0.15 O.sub.n                                             100    46.5 12.6 15.0  7.9                              10   Mo.sub.1 V.sub.0.334 Te.sub.0.2 Nb.sub.0.167 O.sub.n                                           100    63.8 17.6 13.1 10.9                              11   Mo.sub.1 V.sub.0.25 Te.sub.0.2 Nb.sub.0.15 O.sub.n                                             100    51.7 13.6 12.8  8.8                              12   Mo.sub.1 V.sub.0.32 Te.sub.0.2 Nb.sub.0.13 O.sub.n                                             100    67.5 20.2 13.9 12.3                              13   Mo.sub.1 V.sub.0.34 Te.sub.0.2 Nb.sub.0.12 O.sub.n                                             100    78.9 22.2 13.8 15.5                              14   Mo.sub.1 V.sub.0.2 Te.sub.0.2 Nb.sub.0.14 O.sub.n                                              100    54.7 14.9 13.6  9.3                              15   Mo.sub.1 V.sub.0.56 Te.sub.0.2 Nb.sub.0.14 O.sub.n                                             100    107.7                                                                              27.5 13.7 21.1                              16   Mo.sub.1 V.sub.0.45 Te.sub.0.2 Nb.sub.0.05 O.sub.n                                             100    113.9                                                                              24.7 11.4 16.5                              17   Mo.sub.1 V.sub.0.3 Te.sub.0.2 Nb.sub.0.2 O.sub.n                                               100    37.0  9.7 10.7  5.7                              18   Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.2 O.sub.n                                               100    69.9 18.2 10.3 11.2                              19   Mo.sub.1 V.sub.0.3 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                               100    89.9 26.2 14.7 16.8                              20   Mo.sub.1 V.sub.0.48 Te.sub.0.2 Nb.sub.0.12 O.sub.n                                             100    104.7                                                                              26.2 13.3 16.1                              21   Mo.sub.1 V.sub.0.28 Te.sub.0.2 Nb.sub.0.14 O.sub.n                                             100    51.5 14.8 12.2  8.8                              22   Mo.sub.1 V.sub.0.4 Te.sub.0.1 Nb.sub.0.1 O.sub.n                                               100    67.5 18.0 18.0 11.5                              23   Mo.sub.1 V.sub.0.4 Te.sub.0.3 Nb.sub.0.1 O.sub.n                                               100    109.3                                                                              29.2 13.2 17.9                              ______________________________________                                    

                                      TABLE 2                                     __________________________________________________________________________                                            Feed gas     Selectiv-                                     Calcination        composition  ity                                                                                Yield of                                 conditions                                                                             Reaction                                                                           Space                                                                              (mol %)                                                                              Conversion                                                                          acrylo-                                                                            acrylo-                     Complex oxides                                                                             Temp.                                                                             Gas  temp.                                                                              velocity                                                                           propane/                                                                             of propane                                                                          nitrile                                                                            nitrile                     (atomic ratios)                                                                            (°C.)                                                                      stream                                                                             (°C.)                                                                       (hr.sup.-1)                                                                        ammonia/air                                                                          (%)   (%)  (%)                 __________________________________________________________________________    Example 1                                                                             Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                           620 N.sub.2                                                                            420  1,000                                                                              1/1.2/15                                                                             79.4  63.5 50.4                Example 2                                                                             Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                           500 N.sub.2                                                                            400    500                                                                              1/1.2/10                                                                             54.4  39.4 21.4                Example 3                                                                             Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                           600 N.sub.2                                                                            420  1,000                                                                              1/1.2/15                                                                             78.3  61.2 48.0                Comparative                                                                           Mo.sub.1 V.sub.0.4 Te.sub.0.2 O.sub.n                                                      500 N.sub.2                                                                            440  1,000                                                                              1/1.2/15                                                                             43.4  36.7 15.9                Example 1                                                                     Comparative                                                                           Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                           350 air  400    500                                                                              1/1.2/10                                                                             42.9  34.4 14.8                Example 2                                                                     Comparative                                                                           Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub. 0.1 O.sub.n                                          350 air  420    500                                                                              1/1.2/10                                                                             43.2  27.1 11.7                Example 3                                                                     Comparative                                                                           Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                           350 air  440  1,000                                                                              1/1.2/10                                                                             48.8  34.2 16.7                Example 4                                                                     Example 4                                                                             Mo.sub.1 V.sub.0.4 Te.sub.0.2 Sb.sub.0.1 O.sub.n                                           500 N.sub.2                                                                            420    500                                                                              1/1.2/10                                                                             47.7  45.5 21.7                Comparative                                                                           Mo.sub.1 V.sub.0.4 Te.sub.0.2 Sb.sub.0.1 O.sub.n                                           350 air  400    500                                                                              1/1.2/10                                                                             43.0  36.6 15.7                Example 5                                                                     Example 5                                                                             Mo.sub.1 V.sub.0.4 Te.sub.0.2 Al.sub.0.1 O.sub.n                                           500 N.sub.2                                                                            440    500                                                                              1/1.2/10                                                                             60.3  39.1 23.5                Comparative                                                                           Mo.sub.1 V.sub.0.4 Te.sub.0.2 Al.sub.0.1 O.sub.n                                           350 air  420    500                                                                              1/1.2/10                                                                             52.7  33.3 17.5                Example 6                                                                     Example 6                                                                             Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.1 Pd.sub.0.02 O.sub.n                               600 N.sub.2                                                                            420  1,000                                                                              1/1.2/15                                                                             79.4  63.5 50.4                __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________                               Feed gas     Selectiv-                                                        composition  ity for                                                                            Yield for                                         Reaction                                                                           Space                                                                              (mol %)                                                                              Conversion                                                                          acrylo-                                                                            acrylo-                          Example                                                                            Complex oxides                                                                            temp.                                                                              velocity                                                                           propane/                                                                             of propane                                                                          nitrile                                                                            nitrile                          Nos. (atomic ratios)                                                                           (°C.)                                                                       (hr.sup.-1)                                                                        ammonia/air                                                                          (%)   (%)  (%)                              __________________________________________________________________________     7   Mo.sub.1 V.sub.0.3 Te.sub.0.2 Nb.sub.0.15 O.sub.n                                         420  1,000                                                                              1/1.2/15                                                                             89.1  60.0 53.5                              8   Mo.sub.1 V.sub.0.375 Te.sub.0.2 Nb.sub.0.175 O.sub.n                                      420  1,000                                                                              1/1.2/15                                                                             88.4  52.8 46.7                              9   Mo.sub.1 V.sub.0.35 Te.sub.0.2 Nb.sub.0.15 O.sub.n                                        410  1,000                                                                              1/1.2/15                                                                             86.0  55.3 47.6                             10   Mo.sub.1 V.sub.0.334 Te.sub.0.2 Nb.sub.0.167 O.sub.n                                      430  1,000                                                                              1/1.2/15                                                                             90.4  55.9 50.9                             11   Mo.sub.1 V.sub.0.25 Te.sub.0.2 Nb.sub.0.15 O.sub.n                                        400  1,000                                                                              1/1.2/15                                                                             75.3  60.2 45.3                             12   Mo.sub.1 V.sub.0.32 Te.sub.0.2 Nb.sub.0.13 O.sub.n                                        420  1,000                                                                              1/1.2/15                                                                             92.7  57.5 53.3                             13   Mo.sub.1 V.sub.0.39 Te.sub.0.2 Nb.sub.0.12 O.sub.n                                        420  1,000                                                                              1/1.2/15                                                                             91.0  54.5 49.6                             14   Mo.sub.1 V.sub.0.2 Te.sub.0.2 Nb.sub.0.14 O.sub.n                                         400  1,000                                                                              1/1.2/15                                                                             60.5  64.0 38.7                             15   Mo.sub.1 V.sub.0.56 Te.sub.0.2 Nb.sub.0.14 O.sub.n                                        430  1,000                                                                              1/1.2/15                                                                             50.6  62.3 31.5                             16   Mo.sub.1 V.sub.0.45 Te.sub.0.2 Nb.sub.0.05 O.sub.n                                        430  1,000                                                                              1/1.2/15                                                                             52.4  56.3 29.5                             17   Mo.sub.1 V.sub.0.3 Te.sub.0.2 Nb.sub.0.2 O.sub.n                                          440  1,000                                                                              1/1.2/15                                                                             77.2  56.2 43.4                             18   Mo.sub.1 V.sub.0.4 Te.sub.0.2 Nb.sub.0.2 O.sub.n                                          430  1,000                                                                              1/1.2/15                                                                             79.6  61.7 49.1                             19   Mo.sub.1 V.sub.0.3 Te.sub.0.2 Nb.sub.0.1 O.sub.n                                          420  1,000                                                                              1/1.2/15                                                                             83.0  62.1 51.6                             20   Mo.sub.1 V.sub.0.48 Te.sub.0.2 Nb.sub.0.12 O.sub.n                                        430  1,000                                                                              1/1.2/15                                                                             75.4  59.3 44.7                             21   Mo.sub.1 V.sub.0.28 Te.sub.0.2 Nb.sub.0.14 O.sub.n                                        410  1,000                                                                              1/1.2/15                                                                             82.8  63.3 52.4                             22   Mo.sub.1 V.sub.0.4 Te.sub.0.1 Nb.sub.0.1 O.sub.n                                          430    500                                                                              1/1.2/10                                                                             67.7  56.1 38.0                             23   Mo.sub.1 V.sub.0.4 Te.sub.0.3 Nb.sub.0.1 O.sub.n                                          420  1,000                                                                              1/1.2/15                                                                             44.6  48.6 21.7                             __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________                   Feed gas     Selectiv-                                                        composition  ity for                                                                            Yield of                                               Space                                                                              (mol %)                                                                              Conversion                                                                          acrylo-                                                                            acrylo-                                      Example                                                                            Temp.                                                                              velocity                                                                           propane/                                                                             of propane                                                                          nitrile                                                                            nitrile                                      Nos. (°C.)                                                                       (hr.sup.-1)                                                                        ammonia/air                                                                          (%)   (%)  (%)                                          __________________________________________________________________________    24   420  1,000                                                                              1/0.7/15                                                                             82.5  53.1 43.8                                         25   420  1,000                                                                              1/0.9/15                                                                             82.8  57.5 47.6                                         26   420  1,000                                                                              1/1.5/15                                                                             81.4  60.9 49.6                                         27   420  1,000                                                                              1/1.2/10                                                                             62.9  63.8 40.1                                         28   420  1,000                                                                              1/1.2/17                                                                             82.6  57.6 47.5                                         29   420    500                                                                              1/1.2/10                                                                             63.0  56.6 35.7                                         30   420    800                                                                              1/1.2/15                                                                             84.9  57.9 49.2                                         31   420  1,200                                                                              1/1.2/15                                                                             77.8  61.7 48.0                                         32   410  1,000                                                                              1/0.7/15                                                                             76.2  59.1 45.0                                         __________________________________________________________________________

EXAMPLE 33

A complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23 Nb₀.12 O_(n)was prepared as follows.

In 325 ml of warm water, 15.7 g of ammonium metavanadate was dissolved,and 23.6 g of telluric acid and 78.9 g of ammonium paramolybdate weresequentially added thereto to obtain a uniform aqueous solution.Further, 117.5 g of an aqueous ammonium niobium oxalate solution havinga niobium concentration of 0.456 mol/kg was added thereto to obtain aslurry. This slurry was evaporated to dryness to obtain a solid. Thissolid was molded into a tablet of 5 mm in diameter and 3 mm in length bya tabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 600° C. for two hours.

The powder X-ray diffraction of the complex oxide thus obtained wasmeasured (using Cu-Kα-rays), whereby main diffraction peaks wereobserved at diffraction angles of 2θ (°) of 22.1 (100), 28.2 (90.0),36.2 (25.7), 45.1 (15.2) and 50.0 (16.3) (the numerical values in theblackets indicate the relative peak intensities based on the peak at22.1° being 100).

Then, 30 g of the complex oxide was pulverized in a mortar, and 0.3 g oftetravalent antimony oxide (Sb₂ O₄) was added and mixed thereto. Thismixture was molded into a tablet of 5 mm in diameter and 3 mm in lengthby a tabletting machine, followed by pulverization and sieving to obtaina powder of from 16 to 28 mesh. The powder was then calcined in anitrogen stream at 500° C. for two hours.

0.5 ml of the solid catalyst thus obtained, was charged into a reactor,and the gas phase catalytic reaction was conducted at a reactiontemperature of 410° C. and at a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.The results are shown in Table 5.

EXAMPLE 34

A solid catalyst was prepared in the same manner as in Example 33 exceptthat the amount of the tetravalent antimony oxide (Sb₂ O₄) in Example 33was changed to 0.15 g, and the reaction was conducted under the sameconditions as in Example 33. The results are shown in Table 5.

EXAMPLE 35

A solid catalyst was prepared in the same manner as in Example 34 exceptthat the calcination after the addition of the tetravalent antimonyoxide in Example 34 was conducted under a nitrogen stream at 550° C. fortwo hours, and the reaction was conducted under the same conditions asin Example 33. The results are shown in Table 5.

EXAMPLE 36

30 g of the same complex oxide as in Example 33 was pulverized in anagate mortar, and 3 g of an aqueous ammonium antimony tartarate solution(corresponding to 10% by weight of Sb₂ O₃) was added and mixed thereto.The solid of this mixture was molded into a tablet of 5 mm in diameterand 3 mm in length by a tabletting machine, followed by pulverizationand sieving to obtain a powder of from 16 to 28 mesh. The powder wascalcined in an air stream at 300° C. for one hour and further in anitrogen stream at 500° C. for two hours. Using the solid catalyst thusobtained, the reaction was conducted under the same conditions as inExample 33. The results are shown in Table 5.

EXAMPLE 37

Using a complex oxide comprising Mo, V, Te and Nb prepared in the samemanner as in Example 33 except that antimony oxide was not added, thereaction was conducted under the same conditions as in Example 33. Theresults are shown in Table 5.

EXAMPLE 38

A complex oxide having the same catalyst composition as in Example 33was prepared under a condition where tetravalent antimony oxide (Sb₂ O₄)was present from the initial stage, as opposed to adding tetravalentantimony oxide (Sb₂ O₄) after preparing a complex oxide having anempirical formula Mo₁ V₀.3 Te₀.23 Nb₀.12 O_(n).

Namely, 15.7 g of ammonium metavanadate was dissolved in 325 ml of warmwater, and 23.6 g of telluric acid and 78.9 g of ammonium paramolybdatewere sequentially added to obtain a uniform aqueous solution. Further,117.5 g of an aqueous ammonium niobium oxalate solution having a niobiumconcentration of 0.456 mol/kg was mixed thereto to obtain a slurry. Tothis slurry, 0.98 g of tetravalent antimony oxide (Sb₂ O₄) was furtheradded and mixed. This slurry was evaporated to dryness to obtain asolid. This solid was molded into a tablet of 5 mm in diameter and 3 mmin length by a tabletting machine, followed by pulverization and sievingto obtain a powder of from 16 to 28 mesh. The powder was calcined in anitrogen stream at 600° C. for two hours.

Using the solid catalyst thus obtained, the reaction was conducted underthe same conditions as in Example 33. The results are shown in Table 5.

EXAMPLE 39

A complex oxide was prepared in the same manner as in Example 38 exceptthat the calcination in a nitrogen stream in Example 38 was conducted at500° C. for two hours, and the reaction was conducted under the sameconditions as in Example 33. The results are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                                         Selectivity                                                         Conversion                                                                              for        Yield of                                                 of propane                                                                              acrylonitrile                                                                            acrylonitrile                                            (%)       (%)        (%)                                               ______________________________________                                        Example 33                                                                             91.5        63.7       58.3                                          Example 34                                                                             89.3        63.4       56.7                                          Example 35                                                                             86.5        65.6       56.7                                          Example 36                                                                             88.1        63.8       56.2                                          Example 37                                                                             86.7        63.5       55.1                                          Example 38                                                                             67.2        49.4       33.2                                          Example 39                                                                             45.9        48.3       22.2                                          ______________________________________                                    

EXAMPLES 40 TO 68

Using the solid catalyst prepared in Example 33, reactions wereconducted under various conditions, and the results are shown in Table6.

EXAMPLES 69 TO 102

Using the solid catalyst prepared in Example 34, reactions wereconducted under various conditions, and the results are shown in Table7.

EXAMPLES 103 TO 109

Using the solid catalyst prepared in Example 33, reactions wereconducted under various conditions, and the results are shown in Table8.

When the Examples in Table 8 are compared with the Examples in Tables 6and 7, it is evident that under the same reaction conditions, theselectivity and yield are higher in a case where antimony oxide wasadded later than in a case where antimony oxide was not added later.

                                      TABLE 6                                     __________________________________________________________________________                   Feed gas     Selectiv-                                                        composition  ity for                                                                            Yield of                                          Space                                                                              Reaction                                                                           (mol %)                                                                              Conversion                                                                          acrylo-                                                                            acrylo-                                      Example                                                                            velocity                                                                           temp.                                                                              propane/                                                                             of propane                                                                          nitrile                                                                            nitrile                                      Nos. (hr.sup.-1)                                                                        (°C.)                                                                       ammonia/air                                                                          (%)   (%)  (%)                                          __________________________________________________________________________    40   1,000                                                                              410  1/0.6/15                                                                             90.0  53.4 48.1                                         41   1,000                                                                              410  1/0.75/15                                                                            89.9  58.3 52.4                                         42   1,000                                                                              410  1/0.9/15                                                                             89.6  61.9 55.5                                         43   1,000                                                                              410  1/1.05/15                                                                            90.4  63.0 57.0                                         44   1,000                                                                              410  1/1.35/15                                                                            91.6  64.3 58.9                                         45   1,000                                                                              410  1/1.5/15                                                                             90.9  64.9 59.0                                         46   1,000                                                                              410  1/1.65/15                                                                            90.4  65.0 58.8                                         47   1,000                                                                              410  1/1.8/15                                                                             89.4  65.2 58.2                                         48   1,200                                                                              410  1/0.75/10                                                                            75.7  66.8 50.6                                         49   1,200                                                                              410  1/0.9/10                                                                             75.0  68.6 51.5                                         50   1,200                                                                              410  1/0.75/12                                                                            83.7  62.6 52.3                                         51   1.200                                                                              410  1/0.9/12                                                                             83.6  66.9 56.0                                         52   1,200                                                                              410  1/1.2/12                                                                             83.1  68.8 57.2                                         53   1,200                                                                              410  1/0.75/15                                                                            86.3  61.7 53.2                                         54   1,200                                                                              410  1/0.9/15                                                                             87.1  63.8 55.5                                         55   1,200                                                                              410  1/1.2/15                                                                             86.3  66.3 57.2                                         56   1,200                                                                              410  1/1.5/15                                                                             86.2  66.9 57.7                                         57   1,500                                                                              410  1/0.75/10                                                                            73.7  66.5 49.0                                         58   1,500                                                                              410  1/0.9/10                                                                             74.3  68.2 50.7                                         59   1,500                                                                              410  1/1.2/10                                                                             68.9  68.7 47.3                                         60   1,500                                                                              410  1/0.75/12                                                                            79.5  66.1 52.6                                         61   1,500                                                                              410  1/0.9/12                                                                             80.4  69.0 55.4                                         62   1,500                                                                              410  1/1.2/12                                                                             79.5  70.4 55.9                                         63   1,500                                                                              410  1/0.75/15                                                                            81.5  64.9 52.9                                         64   1,500                                                                              410  1/0.9/15                                                                             82.0  66.9 54.8                                         65   1,500                                                                              410  1/1.2/15                                                                             82.1  67.3 55.3                                         66   1,500                                                                              410  1/1.5/15                                                                             81.9  68.9 56.4                                         67   1,500                                                                              400  1/1.2/15                                                                             77.1  68.6 52.9                                         68   1,500                                                                              420  1/1.2/15                                                                             88.3  63.7 56.2                                         __________________________________________________________________________

                                      TABLE 7                                     __________________________________________________________________________                   Feed gas     Selectiv-                                                        composition  ity for                                                                            Yield of                                          Space                                                                              Reaction                                                                           (mol %)                                                                              Conversion                                                                          acrylo-                                                                            acrylo-                                      Example                                                                            velocity                                                                           temp.                                                                              propane/                                                                             of propane                                                                          nitrile                                                                            nitrile                                      Nos. (hr.sup.-1)                                                                        (°C.)                                                                       ammonia/air                                                                          (%)   (%)  (%)                                          __________________________________________________________________________    69   1,000                                                                              400  1/0.6/15                                                                             89.5  56.9 51.0                                         70   1,000                                                                              400  1/0.75/15                                                                            89.8  60.9 54.7                                         71   1,000                                                                              400  1/0.9/15                                                                             89.8  63.2 56.8                                         72   1,000                                                                              400  1/1.5/15                                                                             88.2  61.9 54.6                                         73   1,000                                                                              400  1/0.75/15                                                                            77.5  64.2 49.8                                         74   1,000                                                                              400  1/0.75/12                                                                            87.3  63.7 55.6                                         75   1,000                                                                              400  1/0.9/12                                                                             87.0  64.9 56.5                                         76   1,000                                                                              400  1/1.2/12                                                                             83.4  63.5 52.9                                         77   1,200                                                                              400  1/0.75/10                                                                            77.8  67.1 52.1                                         78   1,200                                                                              400  1/0.9/10                                                                             76.7  67.7 51.9                                         79   1,200                                                                              400  1/0.75/12                                                                            83.9  66.2 55.5                                         80   1,200                                                                              400  1/0.9/12                                                                             83.4  67.6 56.4                                         81   1,200                                                                              400  1/1.2/12                                                                             82.0  66.7 54.8                                         82   1,200                                                                              410  1/0.9/12                                                                             87.5  63.3 55.4                                         83   1,200                                                                              400  1/0.75/15                                                                            85.4  64.5 55.1                                         84   1,200                                                                              410  1/0.75/15                                                                            90.9  59.6 54.2                                         85   1,200                                                                              400  1/0.9/15                                                                             85.5  66.8 57.2                                         86   1,200                                                                              410  1/0.9/15                                                                             90.3  62.6 56.5                                         87   1,200                                                                              400  1/1.2/15                                                                             86.2  64.5 55.6                                         88   1,200                                                                              410  1/1.2/15                                                                             91.2  63.5 57.9                                         89   1,200                                                                              400  1/1.5/15                                                                             84.8  64.1 54.3                                         90   1,200                                                                              410  1/1.5/15                                                                             91.0  65.5 59.7                                         91   1,200                                                                              400  1/1.8/15                                                                             89.3  65.0 58.1                                         92   1,500                                                                              400  1/0.6/10                                                                             75.3  67.5 50.8                                         93   1,500                                                                              400  1/0.75/10                                                                            75.6  69.0 52.2                                         94   1,500                                                                              400  1/0.9/10                                                                             73.9  69.4 51.3                                         95   1,500                                                                              400  1/0.75/12                                                                            78.9  68.3 53.9                                         96   1,500                                                                              400  1/0.75/12                                                                            78.5  68.9 54.1                                         97   1,500                                                                              410  1/0.9/12                                                                             83.3  67.5 56.2                                         98   1,500                                                                              400  1/1.2/12                                                                             77.3  67.3 52.0                                         99   1,500                                                                              410  1/0.9/15                                                                             86.4  64.8 55.9                                         100  1,500                                                                              410  1/1.2/15                                                                             87.1  66.6 58.1                                         101  1,500                                                                              410  1/1.5/15                                                                             86.2  67.1 57.8                                         102  1,500                                                                              410  1/1.8/15                                                                             85.4  66.8 57.1                                         __________________________________________________________________________

                                      TABLE 8                                     __________________________________________________________________________                   Feed gas         Selectivity for                                                                       Yield of                                   Space                                                                              Reaction                                                                           composition (mol %)                                                                      Conversion                                                                          acrylo- acrylo-                               Example                                                                            velocity                                                                           temp.                                                                              propane/   of propane                                                                          nitrile nitrile                               Nos. (hr.sup.-1)                                                                        (°C.)                                                                       ammonia/air                                                                              (%)   (%)     (%)                                   __________________________________________________________________________    103  1,000                                                                              410  1/0.6/15   83.0  56.8    47.1                                  104  1,000                                                                              410  1/0.75/15  82.3  61.4    50.5                                  105  1,000                                                                              410  1/0.9/15   82.8  64.2    53.1                                  106  1,000                                                                              410  1/1.5/15   82.8  66.2    54.8                                  107  1,000                                                                              410  1/1.8/15   80.6  63.6    51.3                                  108  1,200                                                                              410  1/0.75/10  73.8  65.3    48.2                                  109  1,500                                                                              410  1/0.75/10  73.8  65.3    48.2                                  __________________________________________________________________________

EXAMPLES 110 TO 114

A complex oxide having an empirical formula Mo₁ V₀.4 Te₀.2 Nb₀.1 O_(n)was prepared as follows.

In 117 ml of warm water, 4.21 g of ammonium metavanadate was dissolved,and 4.13 g of telluric acid and 15.9 g of ammonium paramolybdate weresequentially added thereto to obtain a uniform aqueous solution.Further, 21.9 g of an aqueous ammonium niobium oxalate solution having aniobium concentration of 0.41 mol/kg was mixed thereto to obtain aslurry. This slurry was evaporated to dryness to obtain a solid. Thissolid was molded into a tablet of 5 mm in diameter and 3 mm in length bya tabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 600° C. for two hours.

The powder X-ray diffraction of the complex oxide thus obtained wasmeasured (using Cu-Kα-rays), whereby main diffraction peaks atdiffraction angles of 2θ (°) of 22.1 (100), 28.2 (79.5), 36.2 (21.0),45.2 (10.9) and 50.0 (12.3) were observed (the numerical values in thebrackets represent relative peak intensities based on the peak at 22.1°being 100).

Then, 10 g of the complex oxide was pulverized in a mortar, and 0.1 oftrivalent antimony oxide (Sb₂ O₃) was further added and mixed thereto.This mixture was molded into a tablet of 5 mm in diameter and 3 mm inlength by a tabletting machine, followed by pulverization and sieving toobtain a powder of from 16 to 28 mesh. The powder was calcined in anitrogen stream at 600° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and reactions were conducted under various conditions. The results areshown in Table 9.

COMPARATIVE EXAMPLES 115 TO 118

Using a complex oxide comprising Mo, V, Te and Nb prepared in the samemanner as in Example 110 except that antimony oxide was notincorporated, reactions were conducted under various conditions, and theresults are shown in Table 9.

Even when the reaction temperature was raised to be higher by 10° C.than Example 115 to increase the conversion of propane, the yield andselectivity are higher when antimony oxide was added, as is evident fromthe comparison of Examples having the same feed gas composition.

                                      TABLE 9                                     __________________________________________________________________________                   Feed gas         Selectivity for                                                                       Yield of                                   Space                                                                              Reaction                                                                           composition (mol %)                                                                      Conversion                                                                          acrylo- acrylo-                               Example                                                                            velocity                                                                           temp.                                                                              propane/   of propane                                                                          nitrile nitrile                               Nos. (hr.sup.-1)                                                                        (°C.)                                                                       ammonia/air                                                                              (%)   (%)     (%)                                   __________________________________________________________________________    110  1,000                                                                              420  1/1.2/15   89.3  60.1    53.7                                  111  1,000                                                                              420  1/0.6/15   90.1  50.7    45.7                                  112  1,000                                                                              420   1/0.75/15 90.4  55.7    50.4                                  113  1,000                                                                              420  1/0.9/15   90.4  58.2    52.7                                  114  1,000                                                                              420  1/1.5/15   87.9  59.8    52.6                                  115  1,000                                                                              430  1/0.6/15   88.2  47.0    41.5                                  116  1,000                                                                              430  1/0.9/15   88.5  56.0    49.5                                  117  1,000                                                                              430  1/1.2/15   88.2  58.5    51.6                                  118  1,000                                                                              430  1/1.5/15   86.5  59.0    51.0                                  __________________________________________________________________________

EXAMPLES 119 to 122

A catalyst was prepared in the same manner as in Example 110 except thattetravalent antimony oxide (Sb₂ O₄) was used for the addition ofantimony oxide to the complex oxide comprising Mo, V, Te and Nb inExample 110, and reactions were conducted under various conditions. Theresults are shown in Table 10.

EXAMPLE 123

A complex oxide having the same catalyst composition as in Example 110was prepared under such a condition that tetravalent antimony oxide (Sb₂O₄) was present from the initial stage as opposed to adding tetravalentantimony oxide (Sb₂ O₄) after the preparation of the complex oxidehaving an empirical formula Mo₁ V₀.4 Te₀.2 Nb₀.1 O_(n).

Namely, in 117 ml of warm water, 4.21 g of ammonium metavanadate wasdissolved, and 4.13 g of telluric acid and 15.9 g of ammoniumparamolybdate were sequentially added thereto to obtain a uniformaqueous solution. Further, 21.9 g of an aqueous ammonium niobium oxalatesolution having a niobium concentration of 0.41 mol/kg was added theretoto obtain a slurry. Further, to this slurry, 0.2 g of tetravalentantimony oxide (Sb₂ O₄) was added and mixed. This slurry was evaporatedto dryness to to obtain a solid. This solid was molded into a tablet of5 mm in diameter and 3 mm in length by a tabletting machine, followed bypulverization and sieving to obtain a powder of from 16 to 28 mesh. Thepowder was calcined in a nitrogen stream at 600° C. for two hours.

Using the catalyst thus obtained, the reaction was conducted under theconditions as identified in Table 10. The results are shown in the sameTable.

EXAMPLE 124

A complex oxide was prepared in the same manner as in Example 123 exceptthat the calcination in a nitrogen stream in Example 123 was conductedat 500° C. for two hours, and the reaction was conducted under theconditions as identified in Table 10. The results are also shown in thesame Table.

                                      TABLE 10                                    __________________________________________________________________________                   Feed gas         Selectivity for                                                                       Yield of                                   Space                                                                              Reaction                                                                           composition (mol %)                                                                      Conversion                                                                          acrylo- acrylo-                               Example                                                                            velocity                                                                           temp.                                                                              propane/   of propane                                                                          nitrile nitrile                               Nos. (hr.sup.-1)                                                                        (°C.)                                                                       ammonia/air                                                                              (%)   (%)     (%)                                   __________________________________________________________________________    119  1,000                                                                              420  1/0.6/15   89.8  51.3    46.1                                  120  1,000                                                                              420   1/0.75/15 90.2  57.0    51.5                                  121  1,000                                                                              420  1/0.9/15   90.0  59.2    53.3                                  122  1,000                                                                              420  1/1.2/15   89.4  59.1    52.8                                  123  1,000                                                                              430  1/1.2/15   74.3  59.5    44.2                                  124  1,000                                                                              410  1/1.2/15   41.6  39.6    16.5                                  __________________________________________________________________________

EXAMPLE 125

30 g of the complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 O_(n) prepared as described in Example 33, was pulverized, and0.3 g of orthoboric acid (H₃ BO₃) was added and mixed thereto. Thismixture was molded into a tablet of 5 mm in diameter and 3 mm in lengthby a tabletting machine, followed by pulverization and sieving to obtaina powder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 600° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase catalytic reaction was conducted at a reactiontemperature of 410° C. and a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.The results are shown in Table 11.

EXAMPLE 126

30 g of the complex oxide having an empirical formula Mo₁ V₀.2 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.6 g oforthoboric acid (H₃ BO₃) was added and mixed thereto. This mixture wasmolded into a tablet of 5 mm in diameter and 3 mm in length by atabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase catalytic oxidation reaction of propane was conductedunder the same reaction conditions as in Example 125. The results areshown in Table 11.

EXAMPLE 127

30 g of the complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.9 g oforthoboric acid (H₃ BO₃) was added and mixed thereto. This mixture wasmolded into a tablet of 5 mm in diameter and 3 mm in length by atabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase catalytic oxidation reaction of propane was conductedunder the same reaction conditions as in Example 125. The results areshown in Table 11.

                  TABLE 11                                                        ______________________________________                                                            Selectiv-                                                                     ity for  Yield of                                                  Conversion acrylo-  acrylo-                                                   of propane nitrile  nitrile                                                   (%)        (%)      (%)                                              ______________________________________                                        Example 125                                                                              89.0         63.2     56.2                                         Example 126                                                                              91.6         63.3     58.0                                         Example 127                                                                              87.9         65.5     57.6                                         ______________________________________                                    

EXAMPLE 128

30 g of the complex oxide having an empirical formula Mo₁ V₀.2 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.3 g ofbismuth oxide (Bi₂ O₃) was added and mixed thereto. This mixture wasmolded into a tablet of 5 mm in diameter and 3 mm in length by atabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase catalytic reaction was conducted at a reactiontemperature of 410° C. and a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.The results are shown in Table 12.

EXAMPLE 129

30 g of the complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.6 g ofbismuth oxide (Bi₂ O₃) was added and mixed thereto. This mixture wasmolded into a tablet of 5 mm in diameter and 3 mm in length by atabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase oxidation reaction of propane was conducted under thesame reaction conditions as in Example 128. The results are shown inTable 12.

EXAMPLE 130

A solid catalyst was prepared in the same manner as in Example 129except that the temperature for calcination in a nitrogen stream afterthe addition of bismuth oxide in Example 129 was changed to 800° C., anda gas phase catalytic oxidation reaction of propane was conducted in thesame manner as in Example 129. the results are shown in Table 12.

EXAMPLE 131

30 g of the complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.9 g ofbismuth oxide (Bi₂ O₃) was added and mixed thereto. This mixture wasmolded into a tablet of 5 mm in diameter and 3 mm in length by atabletting machine, followed by pulverization and sieving to obtain apowder of from 16 to 28 mesh. The powder was calcined in a nitrogenstream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase catalytic oxidation reaction of propane was conductedunder the same reaction conditions as in Example 128. The results areshown in Table 12.

EXAMPLE 132

0.5 ml of the solid catalyst prepared as described in Example 128 wascharged into a reactor, and a gas phase catalytic reaction was conductedat a reaction temperature of 400° C. and at a space velocity SV of 1,000hr⁻¹, by supplying a feed gas in a molar ratio ofpropane:ammonia:air=1:0.75:15. The results are shown in Table 12.

EXAMPLES 133 TO 140

Using the solid catalyst prepared by the method as described in Example129, gas phase catalytic oxidation reactions of propane were conductedunder various reaction conditions. The results are shown in Table 12.

                                      TABLE 12                                    __________________________________________________________________________                   Feed gas         Selectivity for                                                                       Yield of                                   Space                                                                              Reaction                                                                           composition (mol %)                                                                      Conversion                                                                          acrylo- acrylo-                               Example                                                                            velocity                                                                           temp.                                                                              propane/   of propane                                                                          nitrile nitrile                               Nos. (hr.sup.-1)                                                                        (°C.)                                                                       ammonia/air                                                                              (%)   (%)     (%)                                   __________________________________________________________________________    128  1,000                                                                              410  1/1.2/15   96.4  58.5    56.4                                  129  1,000                                                                              410  1/1.2/15   93.5  60.3    56.3                                  130  1,000                                                                              410  1/1.2/15   83.2  67.5    56.2                                  131  1,000                                                                              410  1/1.2/15   90.0  63.6    57.3                                  132  1,000                                                                              400   1/0.75/15 96.5  55.2    53.3                                  133  1,500                                                                              410   1/0.75/12 83.9  66.9    56.2                                  134  1,500                                                                              420   1/0.75/12 87.8  64.9    57.0                                  135  1,500                                                                              410  1/0.9/12   84.0  66.8    56.1                                  136  1,500                                                                              420  1/0.9/12   88.2  66.0    58.2                                  137  1,500                                                                              410   1/0.75/15 85.8  65.8    56.5                                  138  1,500                                                                              420   1/0.75/15 90.4  62.7    58.7                                  139  1,500                                                                              410  1/0.9/15   85.1  66.8    56.9                                  140  1,500                                                                              420  1/0.9/15   90.4  63.6    57.5                                  __________________________________________________________________________

EXAMPLE 141

30 g of the composite oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.3 g ofcerium oxide (CeO₂) was added and mixed thereto. This mixture was moldedinto a tablet of 5 mm in diameter and 3 mm in length by a tablettingmachine, followed by pulverization and sieving to obtain a powder offrom 16 to 28 mesh. The powder was calcined in a nitrogen stream at 600°C. for two hours.

0.5 ml of the solid catalyst thus obtained was charged into a reactor,and a gas phase catalytic reaction was conducted at a reactiontemperature of 142° C. and at a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.The results are shown in Table 13.

EXAMPLE 142

0.5 ml of the solid catalyst prepared as described in Example 141 wascharged into a reactor, and a gas phase catalytic reaction was conductedat a reaction temperature of 430° C. and at a space velocity SV of 1,500hr⁻¹ by supplying a feed gas in a molar ratio ofpropane:ammonia:air=1:1.2:15. The results are shown in Table 13.

EXAMPLE 143

A solid catalyst was prepared in the same manner as in Example 141except that the amount of cerium oxide in Example 141 was changed to 0.6g. 0.5 ml of the solid catalyst thus prepared was charged into areactor, and a gas phase catalytic reaction was conducted at a reactiontemperature of 430° C. and at a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.The results are shown in Table 13.

EXAMPLE 144

0.5 ml of the solid catalyst prepared as described in Example 143 wascharged into a reactor, and a gas phase reaction was conducted at areaction temperature of 440° C. and at a space velocity SV of 1,500 hr⁻¹by supplying a feed gas in a molar ratio ofpropane:ammonia:air=1:1.2:15. The results are shown in Table 13.

COMPARATIVE EXAMPLES 145 to 147

Using a complex oxide comprising Mo, V, Te and Nb prepared in the samemanner as in Examples 141 to 143 except that cerium oxide was not added,a gas phase catalytic oxidation reaction of propane was conducted underthe same conditions as in Examples 141 to 143. The results are shown inTable 13.

                  TABLE 13                                                        ______________________________________                                                                         Selectiv-                                                                     ity for                                                                              Yield of                                     Space    Reaction Conversion                                                                            acrylo-                                                                              acrylo-                               Example                                                                              velocity temp.    of propane                                                                            nitrile                                                                              nitrile                               Nos.   (hr.sup.-1)                                                                            (°C.)                                                                           (%)     (%)    (%)                                   ______________________________________                                        141    1,000    420      93.2    58.4   54.7                                  142    1,500    430      87.5    64.9   56.8                                  143    1,000    430      91.8    57.1   52.4                                  144    1,500    440      88.9    61.2   54.4                                  145    1,000    420      94.2    56.7   53.4                                  146    1,500    430      94.2    57.2   53.8                                  147    1,000    430      91.3    53.8   49.2                                  ______________________________________                                    

EXAMPLE 148

30 g of the complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.225 gof tetravalent antimony oxide (Sb₂ O₄) and 0.6 g of bismuth oxide (Bi₂O₃) were added and mixed thereto. This mixture was molded into a tabletof 5 mm in diameter and 3 mm in length by a tabletting machine, followedby pulverization and sieving to obtain a powder of from 16 to 28 mesh.The powder was calcined in a nitrogen stream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained, was charged into a reactor,and a gas phase reaction was conducted at a reaction temperature of 410°C. and a space velocity SV of 1,000 hr⁻¹ by supplying a feed gas in amolar ratio of propane:ammonia:air=1:1.2:15. The results are shown inTable 14.

EXAMPLE 149

30 g of the complex oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 prepared as described in Example 33, was pulverized, and 0.1125 gof tetravalent antimony oxide (Sb₂ O₄) and 0.3 g of bismuth oxide (Bi₂O₃) were added and mixed thereto. This mixture was molded into a tabletof 5 mm in diameter and 3 mm in length by a tabletting machine, followedby pulverization and sieving to obtain a powder of from 16 to 28 mesh.The powder was calcined in a nitrogen stream at 550° C. for two hours.

0.5 ml of the solid catalyst thus obtained, was charged into a reactor,and a gas phase reaction was conducted at a reaction temperature of 400°C. and a space velocity SV of 1,000 hr⁻¹ by supplying a feed gas in amolar ratio of propane:ammonia:air=1:1.2:15. The results are shown inTable 14.

EXAMPLE 150

0.5 ml of the solid catalyst prepared as described in Example 149 wascharged into a reactor, and a gas phase catalytic reaction was conductedat a reaction temperature of 410° C. and at a space velocity SV of 1,500hr⁻¹ by supplying a feed gas in a molar ratio ofpropane:ammonia:air=1:1.2:15. The results are shown in Table 14.

EXAMPLE 151

To 5 ml of water, 0.277 g of bismuth nitrate pentahydrate (Bi(NO₃)₃.5H₂O) was added, and 0.167 g of tetravalent antimony oxide (Sb₂ O₄) wasfurther added. The mixture was evaporated to dryness. The solid thusobtained was calcined in an air stream at 600° C. for two hours.

To the solid thus obtained, 30 g of the composite oxide having anempirical formula Mo₁ V₀.3 Te₀.23 Nb₀.12 O_(n) prepared as described inExample 33, was added and mixed. This mixture was molded into a tabletof 5 mm in diameter and 3 mm in length by a tabletting machine, followedby pulverization and sieving to obtain a powder of from 16 to 28 mesh.The powder was calcined in a nitrogen stream at 550° C. for two hours.Here, the atomic ratio of Sb:Bi was 2:1.

0.5 ml of a solid catalyst thus obtained, was charged into a reactor,and a gas phase catalytic reaction was conducted at a reactiontemperature of 410° C. and a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.The results are shown in Table 14.

EXAMPLE 152

0.5 ml of a solid catalyst prepared as described in Example 150, wascharged into a reactor, and a gas phase catalytic reaction was conductedat a reaction temperature of 410° C. and at a space velocity SV of 1,500hr⁻¹ by supplying a feed gas in a molar ratio ofpropane:ammonia:air=1:1.2:15. The results are shown in Table 14.

                  TABLE 14                                                        ______________________________________                                                                         Selectiv-                                                                     ity for                                                                              Yield of                                     Space    Reaction Conversion                                                                            acrylo-                                                                              acrylo-                               Example                                                                              velocity temp.    of propane                                                                            nitrile                                                                              nitrile                               Nos.   (hr.sup.-1)                                                                            (°C.)                                                                           (%)     (%)    (%)                                   ______________________________________                                        150    1,000    410      90.1    64.0   57.6                                  151    1,000    400      94.5    59.0   55.8                                  152    1,500    410      90.5    63.7   57.7                                  153    1,000    410      94.8    61.1   57.9                                  154    1,500    410      89.0    64.7   57.6                                  ______________________________________                                    

EXAMPLE 155

30 g of the composite oxide having an empirical formula Mo₁ V₀.3 Te₀.23Nb₀.12 O_(n) prepared as described in Example 33, was pulverized, and0.225 g of tetravalent antimony oxide (Sb₂ O₄) was added and mixedthereto. This mixture was molded into a tablet of 5 mm in diameter and 3mm in length by a tabletting machine, followed by pulverization andsieving to obtain a product of from 16 to 28 mesh. The powder wascalcined in a nitrogen stream at 550° C. for two hours. 0.5 ml of asolid catalyst thus obtained was charged into a reactor, and a gas phasecatalytic reaction was conducted at a reaction temperature of 420° C.and at a space velocity SV of 1,000 hr⁻¹ by supplying a feed gas in amolar ratio of isobutane:ammonia:air=1:1.2:15.

As a result, the conversion of isobutane was 61.4%, the selectivity formethacrylonitrile was 33.0, and the yield of methacrylonitrile was20.3%.

EXAMPLE 156

Using a complex oxide comprising Mo, V, Te and Nb prepared in the samemanner as in Example 155 except that antimony oxide was not added, a gasphase catalytic oxidation reaction of isobutane was conducted under thesame conditions as in Example 155.

As a result, the conversion of isobutane was 64.1%, the selectivity formethacrylonitrile was 29.7%, and the yield of methacrylonitrile was18.1%.

EXAMPLE 157

A material having silica incorporated in an amount of 10% by weight,based on the total amount, to a complex oxide having an empiricalformula Mo₁ V₀.3 Te₀.23 Nb₀.12 O_(n), was prepared as follows.

In 117 ml of warm water, 3.79 g of ammonium metavanadate was dissolved,and 3.72 g of telluric acid and 14.30 g of ammonium paramolybdate weresequentially added thereto to obtain a uniform aqueous solution.Further, 3.59 g of ammonium niobium oxalate dissolved in 17.9 ml ofwater and 10.24 g of silica sol (silica content: 20% by weight) wereadded thereto to obtain a slurry. This slurry was evaporated to drynessat 150° C. to obtain a dried product.

This dried product was molded into a tablet of 5 mm in diameter and 3 mmin length by a tabletting machine, followed by pulverization and sievingto obtain a powder of from 16 to 28 mesh. The powder was calcined in anitrogen stream at a temperature of 600° C. for 4 hours.

The powder X-ray diffraction of the complex oxide thus obtained, wasmeasured, whereby main diffraction peaks were observed at diffractionangles of 2θ (°) of 22.1 (100), 28.2 (41.7), 36.2 (10.0), 45.2 (13.1)and 50.1 (7.1) (the numerical values in the brackets indicate therelative peak intensities based on peak at 22.1° being 100).

0.5 ml of the material thus obtained was charged into a reactor, and agas phase catalytic oxidation reaction was conducted at a reactiontemperature of 420° C. and a space velocity SV of 1,000 hr⁻¹ bysupplying a feed gas in a molar ratio of propane:ammonia:air=1:1.2:15.As a result, the conversion of propane was 88.9%, the selectivity foracrylonitrile was 60.5%, and the yield of acrylonitrile was 53.8%.

EXAMPLE 158

A gas phase catalytic oxidation reaction of isobutane was conducted inthe same manner as in Example 157 except that the complex oxide ofExample 3 was used.

As a result, the conversion of isobutane was 52.1%, the selectivity formethacrylonitrile was 31.0%, and the yield of methacrylonitrile was16.2%.

COMPARATIVE EXAMPLE 7

A gas phase catalytic oxidation reaction of isobutane was conducted inthe same manner as in Example 157 except that the complex oxide ofComparative Example 2 was used.

As a result, the conversion of isobutane was 11.0%, the selectivity formethacrylonitrile was 42.7%, and the yield of methacrylonitrile was4.7%.

According to the process of the present invention, it is possible toproduce a desired nitrile at a relatively low temperature at a level offrom 400° to 450° C. in good yield without necessity of the presence ofa halide or water in the reaction system, by using a novel complex oxidecatalyst and an alkane as the starting material.

We claim:
 1. A process for preparing an α, β-ethylenically unsaturatednitrile, which comprises subjecting an alkane of 3 to 7 carbon atoms andammonia in the gaseous state to catalytic oxidation in the presence of acatalyst under a stream of molecular oxygen gas at an elevated vaporphase temperature and at a pressure and for a time sufficient to preparesaid α,β-ethylenically unsaturated nitrile, which catalyst satisfies thefollowing conditions (1) and (2):(1) the catalyst is represented by theempirical formula (I):

    Mo.sub.a B.sub.b Te.sub.c X.sub.x O.sub.n                  (I)

wherein X is at least one element selected from the group consisting ofNb, Ta, W, Ti Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B andCe, and wherein a is 1, b is 0.01 to 1.0, c is 0.01 to 1.0, and x is0.01 to 1.0, and n is a number such that the total valency of the metalelements is satisfied; and (2) the catalyst has X-ray diffraction peaksat the following angles of 2θ in its X-ray diffraction pattern:

    ______________________________________                                        Diffraction angles of 2θ (°)                                     ______________________________________                                                     22.1 ± 0.3                                                                 28.2 ± 0.3                                                                 36.2 ± 0.3                                                                 45.2 ± 0.3                                                                 50.0 ± 0.3.                                                   ______________________________________                                    


2. The process according to claim 1, wherein in the formula (1), when ais 1, b is 0.1 to 0.6, c is 0.05 to 0.4 and x is 0.01 to 0.6.
 3. Theprocess according to claim 1, wherein in the formula (1), X is Nb. 4.The process according to claim 1, wherein the X-ray diffraction peaks inthe X-ray diffraction pattern of the catalyst have the followingcharacteristics:

    ______________________________________                                        Diffraction angles of 2θ (°)                                                       Relative intensity                                          ______________________________________                                        22.1 ± 0.3     100                                                         28.2 ± 0.3     20 to 150                                                   36.2 ± 0.3     5 to 60                                                     45.2 ± 0.3     2 to 40                                                     50.0 ± 0.3     2 to 40                                                     ______________________________________                                    


5. The process according to claim 1, wherein the catalyst is prepared bydrying an aqueous solution containing compounds of molybdenum, vanadiumand tellurium and a compound of at least one element selected from thegroup consisting of Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni,Pd, Pt, Sb, Bi, B and Ce; calcining the dried product in the absence ofoxygen to obtain a complex oxide; adding to the complex oxide an oxidecontaining at least one element selected from the group consisting ofSb, Bi, Ce, and B; and calcining the mixture.
 6. The process accordingto claim 1, wherein the catalyst is prepared by drying an aqueoussolution containing compounds of molybdenum, vanadium, and tellurium anda compound of at least one element selected from the group consisting ofNb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B andCe; calcining the dry product in the absence of oxygen to obtain acomplex oxide; adding to the complex oxide an organic compoundcontaining at least one element selected from the group consisting ofSb, Bi, Ce, and B; and calcining the mixture.
 7. The process accordingto claim 1, wherein the alkane is propane.
 8. The process according toclaim 1, wherein the ammonium is reacted in an amount of from 0.2 to 5moles per mole of alkane.
 9. A process for preparing anα,β-ethylenically unsaturated nitrile, which comprises subjecting analkane of 3 to 7 carbon atoms and ammonia in the gaseous state tocatalytic oxidation in the presence of a catalyst under a stream ofmolecular oxygen gas at an elevated vapor phase temperature and at apressure and for a time sufficient to prepare said α, β-ethylenicallyunsaturated nitrile,said catalyst being obtained by drying an aqueoussolution containing compounds of molybdenum, vanadium and tellurium anda compound of at least one element selected from the group consisting ofNb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B andCe, and calcining the dried product in the absence of oxygen, whereinthe catalyst is represented by the empirical formula (I):

    Mo.sub.a B.sub.b Te.sub.c X.sub.x O.sub.n                  (I)

wherein X is at least one element selected from the group consisting ofNb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B andCe, and wherein a is 1, b is 0.01 to 1.0, c is 0.01 to 1.0, and x is0.01 to 1.0, and n is a number such that the total valency of the metalelements is satisfied; and wherein the catalyst has X-ray diffractionpeaks at the following angles of 2θ in its X-ray diffraction pattern:

    ______________________________________                                        Diffraction angles of 2θ (°)                                     ______________________________________                                                     22.1 ± 0.3                                                                 28.2 ± 0.3                                                                 36.2 ± 0.3                                                                 45.2 ± 0.3                                                                 50.0 ± 0.3.                                                   ______________________________________                                    


10. The process according to claim 9, wherein the calcination isconducted at a temperature of 350° to 700° C.
 11. The process of claim9, which further comprises after calcining the dried product in theabsence of oxygen, adding to the complex oxide thereof an oxidecontaining at least one element selected from the group consisting ofSb, Bi, Ce and B, and calcining the mixture.
 12. The process of claim 9,which further comprises after calcining the dried product in the absenceof oxygen to obtain a complex oxide, adding to the complex oxide anorganic compound containing at least one element selected from the groupconsisting of Sb, Bi, Ce and B, prior to calcining the mixture.